The ability of a guided projectile to track a particular target may be limited by the field of view (FOV) of the guidance system. A relatively narrow FOV may be unable to locate and track targets that fall outside of the FOV, while a larger FOV permits those targets to be tracked. For example, a semi-active laser homing (SALH) system may use a laser to designate a target. The laser radiation bounces off the target and scatters. A guidance system receives the reflected radiation and guides the projectile in the direction of the radiation reflection.
Most SALH targeting systems comprise a combination of detection devices and collection optics. The detection devices detect radiation emanating or reflected from a target, and may include thermal energy, a radar signal, laser energy, or the like. In many existing optical guidance systems, quad cell detectors are used, which tend to increase the expense of the guidance system.
Changing the FOV ordinarily involves increasing the size of the detector and altering the system's lenses. Altering the lenses of the guidance system, however, may reduce the system's effectiveness because less energy may be transmitted to the detector. In addition, increasing the size of the detector tends to add cost and increase package size.